Loss of ability to move all or part of the body; severe loss or impairment of motor function in part due to lesion of the neural or muscular mechanism. Paralysis can be complete or partial, and can occur on one or both sides of your body, one area or throughout the body. Paraplegia is paralysis of the lower half of the body; quadriplegia is paralysis of the upper and lower regions of the body. Paralysis can be due to stroke, nerve diseases, autoimmune diseases or injury.